1. Field of the Invention
The present invention relates to a cooling apparatus for a high-temperature medium by boiling and condensing refrigerant, capable of absorbing heat generated from a high-temperature medium such as a heating body of a semiconductor device or electric device, to cool the high-temperature medium.
2. Description of the Related Art
A cooling apparatus for a high-temperature medium by boiling and condensing refrigerant is disclosed in JP-A-56-147457. This cooling apparatus has a sealed vessel containing liquid refrigerant and a condensing vessel connected to this sealed vessel by two heat transport pipes, and this condensing vessel is made up of a plurality of tubes and a pair of headers. In this apparatus, vapor refrigerant boiled and vaporized by heat from a heat-emitting body is guided through one of the heat transport pipes to the condensing vessel, is cooled and liquefied as it flows through the tubes of the condensing vessel, and flows back to the sealed vessel through the other heat transport pipe. By this means, heat from the heat-emitting body is transported to the condensing vessel by the boiling and condensing action of the refrigerant and released from the tubes through the fins to an outside fluid.
When a CPU used in a personal computer or the like is to be cooled by the cooling apparatus, the board on which the CPU is mounted is not always disposed horizontally and there are cases wherein it is mounted vertically, and in these cases it becomes necessary for the mounting face of the cooling apparatus to which the CPU is attached to be disposed vertically also.
However, in the related art unit described above, because design anticipating the apparatus being used with the heat-emitting body mounting face vertical has not been carried out, when the apparatus is actually used in such an attitude (a vertical attitude), a sufficient cooling performance cannot be attained. That is, when the apparatus as a whole is used stood up so that the heat-emitting body mounting face is vertical, the two heat transport pipes are both at about the same height as the refrigerant liquid surface and vapor of refrigerant boiled in the sealed vessel and liquid refrigerant liquefied in the condensing vessel cannot circulate smoothly and consequently the cooling capacity of the unit falls.
Another cooling apparatus constituting is disclosed in JP-A-8-255857. This cooling apparatus is constructed by stacking a plurality of press-formed plate members and has a refrigerant tank and a plurality of radiating parts. The radiating parts are each formed in the shape of a flat container using two plate members and are disposed in parallel sandwiching fins between them and are connected to each other through refrigerant passages formed at their ends.
However, in the related art unit described above, openings forming the refrigerant passages of the radiating parts are made by deep drawing of a press die. With this method, to obtain the gaps necessary for disposing the fins, it is necessary to make the diameters of the openings large. As a result, because the area over which the fins can be disposed decreases, there has been the problem that it is not possible to obtain a large effective heat transfer area for the overall size of the cooling vessel.
Another cooling apparatus is disclosed in JP-A-7-161888. This cooling apparatus has a refrigerant tank containing liquid refrigerant and a condensing vessel for cooling vapor of refrigerant boiled in this refrigerant tank by heat from a heat-emitting body, and this condensing vessel is provided integrally with the refrigerant tank.
For example inside the casing of a computer, numerous boards on which semiconductor devices are mounted are disposed vertically and with a narrow spacing, and it is difficult to mount the whole of the cooling apparatus inside this kind of narrow space. However, with the related art cooling apparatus described above, because the condensing vessel and the refrigerant tank are integrated, it is impossible for the condensing vessel to be disposed in a position away from the refrigerant tank or for the attitude of the condensing vessel to be changed, and consequently there has been the problem that the cooling apparatus cannot be used in the kind of narrow space described above.
Another cooling apparatus is disclosed in JP-A-8-78589. This cooling apparatus has a refrigerant tank containing liquid refrigerant and a condensing vessel mounted on the top of this refrigerant tank, and the condensing vessel is mounted inclined at an angle of approximately 90.degree. to the refrigerant tank. In this condensing vessel, refrigerant tubes and fins are disposed alternately, headers are connected to openings at the ends of the refrigerant tubes, and the refrigerant tubes are connected together through these headers.
However, in this related art apparatus, because the condensing vessel is mounted inclined at about 90.degree. to the refrigerant tank, when the amount of heat produced by the heat-emitting body is large the size of the condensing vessel becomes large. In particular, when the height of the condensing vessel becomes great, it cannot be used to cool a heat-emitting body installed in a narrow space between boards like a computer chip or the like.
Also, in this related art apparatus, an upper end opening of the refrigerant tank is connected to one of the headers. Because it is inserted into this header from a direction 90.degree. different from the refrigerant tubes, the size of this header becomes large and the proportion of the heat-radiation area with respect to the size of the unit overall becomes small.
And, because the condensing vessel is mounted on the refrigerant tank inclined at about 90.degree. with respect thereto, there has been the problem that assembling it from one direction is difficult and the assemblability thereof is thus poor.